Do you want to locate the merged cells or do you want to remove them?
If you want to remove the merged cells, then select the range to fix (all the
cells on the worksheet is ok with me!).
Then Format|Cells|alignment tab
clear that merge cells checkbox.
If you really only wanted to determine where they were, you could use a divide
an conquer approach.
Select a range
show alignment tab and check that "merge cells" checkbox.
If it's clear, then there are no merged cells in that selection.
If it's not clear, then reduce the size of the range (by half) and check each
half again. (repeat until you've checked all the cells you're interested in.
Or you could use a macro:
Option Explicit
Sub testme()
Dim myCell As Range
Dim resp As Long
For Each myCell In ActiveSheet.UsedRange.Cells
If myCell.MergeCells Then
If myCell.Address = myCell.MergeArea(1).Address Then
resp = MsgBox(prompt:="found: " _
& myCell.MergeArea.Address & vbLf & _
"Continue looking", Buttons:=vbYesNo)
If resp = vbNo Then
Exit Sub
End If
End If
End If
Next myCell
End Sub
If you're new to macros:
Debra Dalgleish has some notes how to implement macros here:
http://www.contextures.com/xlvba01.html
David McRitchie has an intro to macros:
http://www.mvps.org/dmcritchie/excel/getstarted.htm
Ron de Bruin's intro to macros:
http://www.rondebruin.nl/code.htm
(General, Regular and Standard modules all describe the same thing.)